function shouldBe(actual, expected)
{
    if (actual !== expected)
        throw new Error('bad value: ' + actual);
}

var k = -1;
var o1 = [42.5];
o1[k] = 300.2;

function test1(o)
{
    return k in o;
}
noInline(test1);

for (var i = 0; i < 1e6; ++i)
    shouldBe(test1(o1), true);